This invention is related to a liquid jetting head, for example an ink-jetting recording head capable of jetting a drop of ink from a nozzle by means of vibration of a piezoelectric vibrating member in order to record images or characters on a recording medium. This invention is also related to a method of producing such a liquid jetting head.
As shown in FIGS. 24 and 25, in general, a ink-jetting recording head using longitudinal-vibration type of piezoelectric vibrating members comprises a flowing-path unit 101 provided with a lot of nozzles 108 and a lot of pressure chambers 107. The flowing-path unit 101 is stuck onto a head case 102 containing the piezoelectric vibrating members 106.
In detail, the flowing unit 101 consists of a nozzle plate 103 through which the nozzles 108 are formed in two rows, a flowing-path plate 104 through which the pressure chambers 107 respectively communicating with the nozzles 108 are formed and a vibrating plate 105 that seals lower openings of the pressure chambers 107. The nozzle plate 103, the flowing-path plate 104 and the vibrating plate 105 are layered one on top of another as shown in FIGS. 24 and 25. In the flowing-path plate 104, ink reservoir spaces 109 are formed for storing ink that is introduced into the respective pressure chambers 107. In addition, ink-paths 110 are formed in the flowing-path plate 104 for connecting the respective pressure chambers 107 and the ink reservoir spaces 109.
The head case 102 is made of a synthetic resin. The head case 102 has vertical through spaces 112. The piezoelectric vibrating members 106 are contained in the spaces 112. Tail ends of the piezoelectric vibrating members 106 are fixed to a fixing plate 111, which is attached to the head case 102. Leading surfaces of the piezoelectric vibrating members 106 are fixed to island portions 105A (see FIG. 25) of the vibrating plate 105, respectively.
When a driving signal generated in a driving circuit 114 is inputted to a piezoelectric vibrating member 106 through a flexible circuit board 113, the piezoelectric vibrating member 106 extends and contracts in a longitudinal direction thereof. When the piezoelectric vibrating member 106 extends and contracts, the corresponding island portion 105A of the vibrating plate 105 vibrates to change a pressure of the ink in the corresponding pressure chamber 107. Thus, the ink in the pressure chamber 107 may be jetted from the corresponding nozzle 108 as a drop of the ink. In addition, as shown in FIG. 24, ink supplying ports 115 for supplying the ink to the ink reservoir spaces 109 are formed through the head case 102 and the vibrating plate 105.
As the flowing-path plate 104 of the flowing-path unit 101, conventionally, a plate formed from a silicon mono-crystal substrate by an anisotropic etching process (see Japanese Patent Laid-Open No.9-123448), a plate having a layer made of a photosensitive resin, and an electrocasting plate peeled off from a jig substrate (see Japanese Patent Laid-Open No.6-305142 and Japanese Patent Laid-Open No.9-300635) may be used.
In a case of forming a flowing-path plate 104 from a silicon mono-crystal substrate by an anisotropic etching process, pressure chambers 107 and ink-paths 110 are formed by the etching process. The etched silicon mono-crystal substrate (flowing-path plate 104) is layered with a metal nozzle plate 103 and a vibrating plate 105 via an adhesive material or the like.
However, in general, a linear expansion coefficient of silicon mono-crystal is different from a linear expansion coefficient of metal. Thus, in the flowing-path unit 101 consisting of the layered plates 103-105, a so-called xe2x80x9cwarpxe2x80x9d may occur. This is not serious in the small-sized recording head, but this may result in difficulty in enlarging the size of the recording head.
In a case of forming a flowing-path plate 104 by layering a photosensitive resin on a substrate, there is a problem that a Young""s modulus of the photosensitive resin (flowing-path plate 104) is lower than that of metal or silicon. That is, the photosensitive resin has only a lower rigidity. Thus, if the pressure chambers 107 are arranged more densely, boundary walls therebetween may deform by means of a pressure in an adjacent pressure chamber 107, that is, xe2x80x9ccross-talkxe2x80x9d may occur. Therefore, in the case, it is difficult to densely arrange the nozzles.
In a case of forming a flowing-path plate 104 by pealing off an electrocasting layer formed on a jig substrate, a xe2x80x9cwarpxe2x80x9d of the electrocasting layer may tend to occur during the peeling off from the jig substrate. That is, dimension accuracy of the flowing-path plate 104 may tend to be lower. In addition, the case needs a step of forming the electrocasting layer on the jig substrate and a step of peeling off the electrocasting layer from the jig substrate, which may result in longer time and greater cost.
The object of this invention is to solve the above problems, that is, to provide a liquid jetting head such as an ink-jet recording head wherein a xe2x80x9cwarpxe2x80x9d of a flowing-path plate is prevented so that the liquid jetting head can be advantageously made more accurate, enlarged and made denser.
In order to achieve the object, a liquid jetting head includes: a flowing-path plate through which a flowing-path space is formed as a flowing-path for a liquid; a nozzle plate provided on one side surface of the flowing-path plate, said nozzle plate having a nozzle that is communicated with the flowing-path space; and a sealing plate provided on the other side surface of the flowing-path plate for sealing the flowing-path space; wherein a portion of the other side of the flowing-path space forms a pressure-chamber space; a portion of the other side of the flowing-path plate including at least a portion of the pressure-chamber space is formed by electrocasting; and a pressure-generating unit is provided at a portion of the other side of the sealing plate corresponding to the pressure-chamber space for changing a pressure of the liquid in the pressure-chamber space.
According to the feature, since the portion of the other side of the flowing-path plate is formed by electrocasting, a xe2x80x9cwarpxe2x80x9d of the flowing-path plate may be prevented. Thus, the flowing-path plate may be formed more accurately. In addition, since the portion formed by electrocasting includes at least the portion of the pressure-chamber space, preferably the whole pressure-chamber space, boundary walls defining the pressure-chamber space may have a relatively higher rigidity. Thus, the pressure-chamber spaces may be arranged more densely. Therefore, the liquid jetting head is advantageous in being made denser, made more accurate, and enlarged.
In addition, since the pressure-chamber space is formed as the portion of the flowing-path space, the pressure-chamber space may be easily positioned relative to the nozzle. Thus, it may be prevented that an air bubble is generated and stays in the flowing-path space. In addition, a step of peeling off the electrocasting portion is unnecessary, which is advantageous in cost.
Preferably, the flowing-path plate has a substrate layer and an electrocasting layer formed on the other side surface of the substrate layer by electrocasting. In the case, the liquid jetting head may be easily produced.
For example, preferably, the pressure-chamber space is formed in the electrocasting layer as a through hole having substantially the same shape in a depth direction thereof, the one side surface of the pressure-chamber space is defined by the substrate layer, the other side surface of the pressure-chamber space is defined by the sealing plate, and lateral side surfaces of the pressure-chamber space are defined by the electrtocasting layer. In the case, a communicating hole may be formed in the substrate layer for connecting the pressure-chamber space and the nozzle. The substrate layer and the nozzle plate may be formed integratedly.
Alternatively, the flowing-path plate may have a substrate layer, an electrocasting layer formed on the other side surface of the substrate layer by electrocasting and a second electrocasting layer formed on the one side surface of the substrate layer by electrocasting. In the case, the liquid jetting head may be easily produced as well.
For example, preferably, the pressure-chamber space is formed in the electrocasting layer as a through hole having substantially a same shape in a depth direction thereof, the one side surface of the pressure-chamber space is defined by the substrate layer, the other side surface of the pressure-chamber space is defined by the sealing plate, lateral side surfaces of the pressure-chamber space are defined by the electrtocasting layer, a second pressure-chamber space is formed in the second electrocasting layer as a through hole having substantially a same shape in a depth direction thereof, the second pressure-chamber space is communicated with the nozzle, the one side surface of the second pressure-chamber space is defined by the nozzle plate, the other side surface of the second pressure-chamber space is defined by the substrate layer, and lateral side surfaces of the second pressure-chamber space are defined by the second electrtocasting layer. In the case, a communicating hole may be formed in the substrate layer for connecting the pressure-chamber space and the second pressure-chamber space.
According to the above feature, that is, when the pressure-chamber spaces are formed on both side surfaces of the substrate layer, a thickness of the electrocasting layer and a thickness the second electrocasting layer may be allowed to be thinner. Thus, the electrocasting step may be shortened. In addition, a warp of the electrocasting layer and a warp of the second electrocasting layer may be prevented more extremely.
In addition, preferably, a thermal expansion coefficient of the electrocasting layer and/or a thermal expansion coefficient of the second electrocasting layer are substantially equal to a thermal expansion coefficient of the substrate layer. In the case, a warp of the electrocasting layer and/or a warp of the second electrocasting layer may be prevented more extremely. More preferably, the electrocasting layer and/or the second electrocasting layer are made of nickel or chromium, which is superior in adherence to the substrate layer, rigidity, corrosion resistance or the like. In general, the substrate layer may be made of an electric conductive material.
In addition, preferably, a thickness of the electrocasting layer and/or a thickness of the second electrocasting layer are smaller than a thickness of the substrate layer. In the case, a warp of the electrocasting layer and/or a warp of the second electrocasting layer may be prevented more extremely.
In addition, a liquid reservoir space communicating with the pressure-chamber space may be also formed in the electrocasting layer. In the case, space may be utilized more efficiently. For example, preferably, the liquid reservoir space is formed in the electrocasting layer as a through hole having substantially the same shape in a depth direction thereof, the one side surface of the liquid reservoir space is defined by the substrate layer, the other side surface of the liquid reservoir space is defined by the sealing plate, and lateral side surfaces of the liquid reservoir space are defined by the electrtocasting layer.
Similarly, a second liquid reservoir space communicating with the second pressure-chamber space may be also formed in the second electrocasting layer. For example, preferably, the second liquid reservoir space is formed in the second electrtocasting layer as a through hole having substantially the same shape in a depth direction thereof, the one side surface of the second liquid reservoir space is defined by the nozzle plate, the other side surface of the second liquid reservoir space is defined by the substrate layer, and lateral side surfaces of the second liquid reservoir space are defined by the second electrtocasting layer.
In addition, preferably, the nozzle plate is formed on the one side surface of the flowing-path plate by electrocasting. In the case, the number of parts and the number of steps for manufacturing the liquid jetting head may be reduced. Thus, the accuracy of the liquid jetting head may be improved more, and the cost thereof may be reduced more.
For example, the pressure-generating unit may have a piezoelectric vibrating member that can extend and contract. Alternatively, the pressure-generating unit may have a piezoelectric vibrating member that can bend. In these cases, the sealing plate is a vibrating plate that can deform and vibrate. Alternatively, the pressure-generating unit may have a heater that can heat the liquid in the pressure-chamber space. In the case, the sealing plate has a thermal conductivity.
In addition, this invention is a method of producing a liquid jetting head including: a flowing-path plate through which a flowing-path space is formed as a flowing-path for a liquid; a nozzle plate provided on one side surface of the flowing-path plate, said nozzle plate having a nozzle that is communicated with the flowing-path space; and a sealing plate provided on the other side surface of the flowing-path plate for sealing the flowing-path space; wherein a portion of the other side of the flowing-path space forms a pressure-chamber space; a portion of the other side of the flowing-path plate including at least a portion of the pressure-chamber space is formed by electrocasting; a pressure-generating unit is provided at a portion of the other side of the sealing plate corresponding to the pressure-chamber space for changing a pressure of the liquid in the pressure-chamber space; and the flowing-path plate has a substrate layer and an electrocasting layer formed on the other side surface of the substrate layer by electrocasting; comprising;
a pattern-forming step of forming and sticking a pattern corresponding to a portion of the flowing-path space in the portion of the other side of the flowing-path plate onto the other side surface of the substrate layer,
an electrocasting step of forming the portion of the other side of the flowing-path plate onto the other side surface of the substrate layer by electrocasting in such a manner that the pattern is covered, and
a pattern-removing step of removing the pattern in order to form the portion of the flowing-path space in the portion of the other side of the flowing-path plate.
According to the feature, the liquid jetting head may be produced more accurately by means of the relatively simpler and easier steps.
For example, the pattern-forming step may include: a step of applying a photosensitive resin to the other side surface of the substrate layer; and a step of exposing and developing the applied photosensitive resin according to said pattern. In the case, the pattern may be formed more easily.
If an electrocasting speed is raised in order to increase productivity, a thickness of the portion formed by electrocasting may tend to be uneven. In the case, preferably, the method may further include a grinding step of grinding the other side surface of the flowing-path plate, after the pattern-removing step.
A communicating hole may be formed in the substrate layer for connecting the pressure-chamber space and the nozzle, before the pattern-forming step or after the pattern-removing step.
In addition, this invention is a method of producing a liquid jetting head including: a flowing-path plate through which a flowing-path space is formed as a flowing-path for a liquid; a nozzle plate provided on one side surface of the flowing-path plate, said nozzle plate having a nozzle that is communicated with the flowing-path space; and a sealing plate provided on the other side surface of the flowing-path plate for sealing the flowing-path space; wherein:
a portion of the other side of the flowing-path space forms a pressure-chamber space; a portion of the other side of the flowing-path plate including at least a portion of the pressure-chamber space is formed by electrocasting; a pressure-generating unit is provided at a portion of the other side of the sealing plate corresponding to the pressure-chamber space for changing a pressure of the liquid in the pressure-chamber space;
the flowing-path plate has a substrate layer, an electrocasting layer formed on the other side surface of the substrate layer by electrocasting and a second electrocasting layer formed on the one side surface of the substrate layer by electrocasting;
the pressure-chamber space is formed in the electrocasting layer as a through hole having substantially a same shape in a depth direction thereof; he one side surface of the pressure-chamber space is defined by the substrate layer; the other side surface of the pressure-chamber space is defined by the sealing plate; lateral side surfaces of the pressure-chamber space are defined by the electrtocasting layer; a second pressure-chamber space is formed in the second electrocasting layer as a through hole having substantially a same shape in a depth direction thereof; the second pressure-chamber space is communicated with the nozzle; the one side surface of the second pressure-chamber space is defined by the nozzle plate; the other side surface of the second pressure-chamber space is defined by the substrate layer; lateral side surfaces of the second pressure-chamber space are defined by the second electrtocasting layer; and a communicating hole is formed in the substrate layer for connecting the pressure-chamber space and the second pressure-chamber space; comprising:
a pattern-forming step of forming and sticking a pattern corresponding to the pressure-chamber space onto the other side surface of the substrate layer,
a second pattern-forming step of forming and sticking a second pattern corresponding to the second pressure-chamber space onto the one side surface of the substrate layer,
an electrocasting step of forming the electrocasting layer onto the other side surface of the substrate layer by electrocasting in such a manner that the pattern is covered,
an second electrocasting step of forming the second electrocasting layer onto the one side surface of the substrate layer by electrocasting in such a manner that the second pattern is covered,
a pattern-removing step of removing the pattern in order to form the pressure-chamber space, and
a second pattern-removing step of removing the second pattern in order to form the second pressure-chamber space.
According to the feature, the pressure-chamber spaces may be formed more accurately on both side surfaces of the substrate layer by means of the relatively simpler and easier steps.
In particular, if the pattern-forming step and the second pattern-forming step are conducted at substantially the same time and/or if the pattern-removing step and the second pattern-removing step are conducted at substantially the same time, a time for the steps may be shortened more.
In addition, the liquid reservoir space and/or the second liquid reservoir space may be formed by electrocasting, similarly to the flowing-path space. However, it is unnecessary for the liquid reservoir spaces to be formed accurately. Thus, the liquid reservoir spaces may be formed after the pattern-removing step or after the grinding step.
In addition, this invention is a method of producing a liquid jetting head including: a flowing-path plate through which a flowing-path space is formed as a flowing-path for a liquid; a nozzle plate provided on one side surface of the flowing-path plate, said nozzle plate having a nozzle that is communicated with the flowing-path space; and a sealing plate provided on the other side surface of the flowing-path plate for sealing the flowing-path space; wherein a portion of the other side of the flowing-path space forms a pressure-chamber space; a portion of the other side of the flowing-path plate including at least a portion of the pressure-chamber space is formed by electrocasting; a pressure-generating unit is provided at a portion of the other side of the sealing plate corresponding to the pressure-chamber space for changing a pressure of the liquid in the pressure-chamber space; and the nozzle plate is formed on the one side surface of the flowing-path plate by electrocasting; comprising;
a pattern-forming step of forming and sticking a pattern corresponding to the nozzle of the nozzle plate onto the one side surface of the flowing-path plate,
an electrocasting step of forming the nozzle plate onto the one side surface of the flowing-path plate by electrocasting in such a manner that the pattern is covered, and
a pattern-removing step of removing the pattern in order to form the nozzle.
According to the feature, the nozzle plate may be formed by electrocasting by means of the relatively simpler and easier steps.
For example, the pattern-forming step may include: a step of applying a photosensitive resin to the one side surface of the flowing-path plate; and a step of exposing and developing the applied photosensitive resin according to said pattern. In the case, the pattern may be formed more easily.
The method may further comprise a step of forming a communicating hole to the nozzle in the flowing-path plate, before the pattern-forming step. In the case, preferably, the pattern-forming step is a step of forming and sticking a first pattern to seal the communicating hole and a second pattern corresponding to the nozzle of the nozzle plate.